There are no accurate estimates of the population of Australia before European settlement. Estimates were based on post-1788 observations of a population already reduced by introduced diseases and other factors, and range from a minimum pre-1788 population of 315,000 to over one million people. Recent archaeological evidence suggests that a population of 750,000 Indigenous peoples could have been sustained.

Whatever the size of the Indigenous population before European settlement, it declined dramatically under the impact of new diseases, repressive and often brutal treatment, dispossession, and social and cultural disruption and disintegration (see the article Statistics on the Indigenous Peoples of Australia, in Year Book Australia 1994). The decline of the Indigenous population continued well into the 20th century.

More recently, changing social attitudes, political developments, improved statistical coverage and a broader definition of Indigenous origin have all contributed to the increased likelihood of people identifying as being of Aboriginal or Torres Strait Islander (Indigenous) origin. This is reflected in the large increases in the number of people who are identified as being Indigenous in each Census, increases in excess of those which can be attributed to natural increase in the Indigenous population.

In developing estimates of the size and age structure of the Indigenous population, Census counts are adjusted for undercount as well as other factors, including cases where Indigenous status was not known. These estimates are referred to as 'experimental' estimates of the Indigenous population.

Table 7.22 shows the distribution of the experimental estimated resident Indigenous population, by state and territory, for 1996, 2001 and 2006. The estimates for 1996 and 2001 have been calculated using 2001 population estimates derived from the 2001 Census of Population and Housing and experimental Indigenous life tables to 'reverse survive' the population back to 1991. The estimates for 2006 are based on the 2006 Census of Population and Housing.

The estimated resident Indigenous population at 30 June 2006 was 517,200 people, or 2.5% of the total Australian population. Indigenous people of Aboriginal origin contributed 90% of the total Indigenous population; people of Torres Strait Islander origin comprised 6%, and those of both Aboriginal and Torres Strait Islander origin comprised 4%.

Of the total Indigenous population at 30 June 2006, 148,200 (29%) people lived in New South Wales, 146,400 (28%) in Queensland, 77,900 (15%) in Western Australia and 66,600 (13%) in the Northern Territory. The Northern Territory had the largest proportion of its population who were Indigenous (32%), compared with 4% or less for all other states and the Australian Capital Territory.

7.23 Indigenous population distribution(a) - June 2006

The Indigenous population is a relatively young population, with a median age of 21 years, compared with 37 years for the non-Indigenous population. The younger age structure of the Indigenous population is shown in graph 7.24. In 2006, 37% of Indigenous people were aged under 15 years compared with 19% of non-Indigenous people. People aged 65 years and over comprised 3% of the Indigenous population and 13% of the non-Indigenous population.

7.24 Age distribution of the indigenous and non-indigenous population(a) - June 2006

The age structure of the Indigenous population reflects higher rates of fertility, and deaths occurring at younger ages. Although the total fertility rate among Indigenous women has fallen in recent decades, from around 6 babies per woman in the 1960s to 2.1 babies per woman in 2005, it remains higher than the fertility rate for the total female population (1.8 babies per woman in 2005). In the period 1996-2001, life expectancy at birth was estimated to be 59.4 years for Indigenous males and 64.8 years for Indigenous females. This is well below the 76.6 years and 82.0 years for total males and females respectively, for the 1998-2000 period.

The latest projections of the Indigenous population, produced by the ABS for the period 2002 to 2009, are based on the results of the 2001 Census of Population and Housing. Assuming no further unexplained growth in Census counts of the Indigenous population (low series), Australia's Indigenous population is projected to increase from 458,500 people in 2001 to 528,600 people in 2009. If unexplained growth (that which cannot be attributed to natural increase) were to continue at the same rate as observed between the 1996 and 2001 Censuses, the Indigenous population (high series) would increase to 542,900 people in 2006 and 600,200 people in 2009. The projected average annual growth rate of the Indigenous population is 1.8% for the low series and 3.4% for the high series. These projected growth rates are both higher than the observed increase in the total Australian population for the year ending June 2002 (1.2%).

Indigenous populations of all states and territories are projected to continue growing between 2001 and 2009. The rate of growth in New South Wales is projected to remain constant in both series over the projection period, while the rate of growth is projected to decline in both series in Queensland, South Australia, Western Australia, the Northern Territory and the Australian Capital Territory. For Victoria, the growth rate declines slightly in the high series but remains constant after 2002 in the low series. For Tasmania the growth rate remains constant in the high series but increases slightly in the low series.